Leonardo

tion with Copernicus's astronomical model, is clearly and convincingly presented . Unfortunately, regarding my question about documentation, Stumpel merely notes in passing that it "can be safely guessed" (p.198) that Copernicus knew of the Renaissance theory of art. Surely this is not a satisfactory --or 'safe'-position. Nevertheless , ignoring this weakness in his argument, the article deserves to be read and I am pleased that Stumpel has pursued a piece of research that I procrastinated about for years. References 1. Evelyn Fox Keller, Reflections on Genderand Science (New Haven, Gr: Yale Univ. Press, 1985). 2. See, for example, Gerald Holton, Thematic OriginsofScientijic Thought (Cambridge, MA.: Harvard Univ. Press, 1988, Rev. Ed.). 3. Gerald Holton, "Quanta, Relativity, and Rhetoric ", unpublished manuscript. 4. Peter Gay, Freud:A Lifefor Our Time (New York: Norton, 1988). 5. E. H. Gombrich, Art and Illusion:A Study in the Psychology ofPictorialRepresentation (Princeton, NJ: Princeton Univ. Press, 1960). THE VISUAL NATURE OF COLOR by Patricia Sloane. Design Press, New York, NY, U.S.A., 1989. Distributed by McGraw Hill, New York, NY,U.S.A. 342 pp., illus. Cloth, $29.95. ISBN: 0-8036-550o-X. Reviewed byJoy Turner Luke, Route 1, Box 18, Sperryville, VA 22740, U.S.A. It has been difficult to write this review. In the first place the book is tedious to read, and in the second place it is shot through with errors that are impossible to adequately address in a book review of reasonable length. The author's viewpoint is philosophical and epistemological. She has read a great many books about color and about knowledge. The problem is that, in spite of her academic credentials , her philosophic speculation is in most cases based on misreadings of the technical literature. The following is an attempt to give the flavor of the book and a few examples to indicate the type of problems it presents. It is typical of her general approach that Sloane devotes pages and pages to debating whether or not the commonly used statement, "It looks red," has any validity. The fact that the sentence is an abbreviated way for a speaker to indicate that something appears to be red, although he or she realizes that its appearance may be due to viewing angle or the light source, does not cut any ice with Sloane. She beats the statement to death on theoretical grounds. Early in the book she states, ''Visual comparisons are more accurate than those made by instruments", and references Ralph Evans's Introductionto Colorwritten in 1948. That is 43 years ago, which is a long time in instrument development. The statement figures later in the book in some of her conclusions about colorimetry. It is true that the human eye is very good at perceiving color differences betweenjuxtaposed colors, but modern instruments, well maintained, are much more accurate. This is not to say that identical measurements are obtained from different instruments, but the variation is much smaller than the variation in humanjudgments. An individual'sjudgments about color differences vary from day to day, and the variation in judgments between different individuals is much larger. One study showed that observers frequently reported a color difference between identical color samples. The placement of two colors being compared affects humanjudgments. If the edges of the two colors do not touch, human ability to accurately judge color differences declines. As a matter of fact, even this statement is a simplification since the eye is better at judging lightness differences when the colors are separated by very small distances. The human ability to compare colors is remarkable and perfectly adequate for artists, but industry, where color control and color communication involve a great deal of money, relies on color-measuring instruments. Sloane dismisses color systems, and the Munsell Color system in particular , on the ground that they are not practical since someone specifying a color would need to send one of the color chips, "Removing the swatch from the book to pass it along to the dyers means it will be unavailable if needed again. Sending the entire book means it will be unavailable and may be mislaid." This is rather like arguing that a pencil is not worthwhile because...